Universal rotor mounting



y 4, 1954 D. c. PRINCE 2,677,431

UNIVERSAL ROTOR MOUNTING Filed Oct. 21, 1950 Ifiventor':

.David QPr'ince, 4 M

His Attorney.

Patented May 4, 1 954 UNIVERSAL ROTOR MOUNTING David 0. Prince,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application. October 21, 1950, Serial No. 191,433 1 Claim.(01. 170-16027) This invention relates to rotary wing aircraft and, inparticular, to an improved suspension for a fuselage of an aircraft fromsuch a rotary wing.

In rotary wing aircraft, wherein a fuselage is suspended from a rotatingwing, a serious problem is brought about by the lateral movement of thewing through the air during rotation.

Specifically, in a vertical climb, a rotating wing is given a lift forcedependent upon the rate at which it cuts through still air. If the wingis moved laterally while rotating, however, an unbalanced lift is givento the wing, due to the variation in the relative air velocity acting ona wing in any one revolution. This may best be understood by looking ata rotating blade from above and comparing the portions of a blade withthe face of a clock. Under these conditions, assuming that the plane isflying towards 12 oclock with its win rotating counterclockwise, then at3 o'clock the blade is acted upon by an air velocity equal to theinstantaneous tangential velocity of the wing plus the lateral velocityof the plane. At 12 oclock, the wing is given a lift force sup; pliedonly by its instantaneous tangential velccity; at 9 oclock, the lift issupplied by an air velocity equal to the instantaneous tangentialvelocity of the rotor minus the lateral velocity of the aircraft. At 6oclock, the conditions are similar to those at 12 oclock. It is obvious,then, that in any complete revolution of a wing its lifting force andits drag are cyclically varied.

This cyclic variation in both the lift and drag presents 2 seriousvibrational problem, causin the wing hub to move about its normal orstill air axis.

If a rotating blade and its supporting shaft are rigidly secured to afuselage of an aircraft, then, these vibrations that are produced in theshaft of the rotating blade are transmitted to the fuselage where theyoccasionally reach the harmonic vibration frequency of the plane toproduce disastrous results.

In an attempt to reduce these vibrational forces, spring loaded flaphinges are used to suspend a wing from its supporting hub. Flap hingesallow the blade to change its vertical position relative to the hubwhile the spring absorbs much of the vibration without influencing theaxis. Furthermore, drag hinges which permit oscillation of a wing in itsown plane have been used on such aircraft to reduce the drag efiect ofthe changing of lateral force upon the wing.

While these two innovations have considerably helped the vibrationproblem, the fact that drag hinges allow the blade to oscillate back andforth be more clearly with respect to its static or still air axis isoffset by the fact that the blades are continually changing, passingforward and behind their static position to produce a centrifugal forceon the hub of the wing, which again tends to set up undesirablevibrational effects in the fuselage. With these considerations in mind,it is obvious that there is still much room for improvement in themounting of a rotating blade on the fuselage of a rotary wing aircraft.

It is an object of this invention to provide a new and improved mountingsupport for a rotating blade on the fuselage of an aircraft.

It is a further object of this invention to provide a linkage connectionbetween a rotating blade and the fuselage of the plane that permits therotating blade to move in a plane about its static axis withoutvibrating the fuselage.

It is a still further object of this invention to provide a new andimproved simple method of removing the vibrational forces that effectthe rotor and fuselage of a rotating blade.

Further objects and advantages of this invention will become apparentand the invention will understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichchar-- acterize this invention will be pointed out with particularity inthe claim annexed to and forming a part of this specification.

Briefly, this invention comprises the employment of a double universaljoint and a parallelogram type supporting fuselage of a plane from arotating blade or wing.

t With the combination of the double universal joint and theparallelogram support, vibrational stresses that are set up in the hubof the rotating blade are not transmitted to either the control stickwithin the fuselage or the fuselage itself.

Referring to the drawing, Fig. 1 is a side elevation partly in sectionof the improved suspension system and control; Fig. 2 is a frontelevation primarily, of the improved control; while Fig. 3 is a topelevation of the mechanism shown in Fig. 1.

In the drawing, a rotor l is shown comprising a pair of blades 2 and 3,mounted on a hub 3a. Blade 2 is supported on hub to by a drag hinge 4and a flap hinge 5, while blade 3 is supported on hub So by a drag hinge6 and a flap hinge 1. As has been mentioned, the drag hinges function toabsorb the vibrations produced by the varying drag load on a blade inpassing through changing relative air velocities in one revolution. Theflap hinges absorb the vertical vibradevice for suspending the tioncaused by the fluctuation in lift force, due to varying relative airvelocities in any one revolution. Hub 3a is connected by a shaft 8 to athrust bearing 8a. The thrust bearing 8a, which is mounted in bearinghousing 9, provides vertical support for fuselage 9a of a helicopter orthe like. A universal joint H1 is mounted on bearing housing 9 and isconnected by shaft II to a universal joint l2 and thence by joint member|3 to universal joint l4. Universal joint I4 is rigidly secured to thefuselage 9a.

A plate I1 is secured to bearing housing 9 and is provided with a pairof sockets |8 and I!) which are located 90 apart and in substantiallythe same plane. A ball 20 and a ball 2| are connected by means of rods22 and 23, respectively, to a plate 24 which is rigidly secured tomember l3. Specifically, rod 22 is mounted on plate 24 by means of aball 25 fitting into a socket 26 provided in the plate 24 while rod 23is mounted by means of a ball 21 fitting into a socket .28 at a portiondisplaced 90 from socket 26 and underlying socket |3.

A control stick 29 is rigidly secured to plate 24 and extends down intothe fuselage 9a of the plane. The control stick 29 provides for themovement and tilting of the hub 3a to change the plane of rotation ofthe rotor The operation of the device shown in the drawing is asfollows. Rotor rotates in unison with hub 3a. The rotation of the rotorI may be produced by any external source, such aswing tip jet units, orit may rotate merely through wind-milling action, if this particulardevice or helicopter is used as a glider. The means for rotating rotoris not within the scope of this invention and, consequently, nolimitation is intended to be implied from any particular means ofrotation described. If jet unit type rotation were selected, fuel line3|! would be brought into a pressure coupling 3|, whereupon flexiblehoses 32 and 33 would carry fuel to jet unitsnot shown located on wings2 and 3, respectively.

In the rotation of rotor l, a great dealer the shock produced in theblades due to themovement in the lateral path of the fuselage isabsorbed by the drag hinges 4 and 6. By this is meant that as anincrease drag is .put onto the blade 3-maximum and minimum drag occurwhen the tangential velocity of the blade is parallel to the path of thefuselage-thedrag hinge 6 allows blade 3 to be displaced from the radialline through the axial center of hub 3 .and pin 6a of drag hinge 6. Themovement'of blade 3. off this radial line absorbs some of the shock thatis produced by the varying drag'that is placed on blade 3. Obviously,the same thing happens with blade 2 and drag hinge 4.

Any variation in the vertical position of the blades during one rotationofrotor due to changing relative velocities, as heretofore explained, ispartially absorbed by the flap hinges and Hub 30., as has heretoforebeen described, is rigidly secured to shaft 8, which, in turn, issecured to thrust bearing 8a. Thrust bearing 8a can beof anyconventional form. For example, ball bearings 82) can bepositioned'between two plates 34 and 35 with plate 34 secured .to shaft'8 and plate 35 being an integralpart of bearing.

housing 9. This connection provides. adequate suspension for fuselage90., since bearing housing 9.does not rotate and support is providedbetween fuselage 9a and bearing housing 9 through shaft II and theuniversal joints l0, I2, and I4, previously described.

The universal joints l0, l2, and I4, allow the plane of rotor I to takea convenient position relative to the vertical axis of joint M. Thisplane of rotor is the means for directing the path of fuselage 9a. Thatis, by tilting the plane of the rotor in any one direction, therotor'then' provides a sustaining or lifting force, plus a component ofmovement in the direction of the tilt. Specifically, take the plane ofthe tilt and pass a line perpendicularly through the center of hub 3aand then relegate this line into a vector in a vertical direction and avector in the horizontal direction. The vector in the horizontaldirection then gives the direction of flight oi the fuselage.

The parallel linkage joining plate H with plate 24 allowsfor themovement of hub 3a about the vertical axis through joint l4.Consequently, hub 30. can oscillate in its own plane withouttransmitting these oscillations to plate 24 and joint member I3. Theparallel linkage and the ball and socket joints previously describedprovide for the tilting of the plane of rotor by means of lever 29. Withthis structure, then, the tilt of the plane at rotor I can be controlledand. thus, the direction of flight of the fuselage 9a can be controlled.

More specifically, if lever 29 is pulled counterclockwise with respectto plate 24 (see Fig. 1), then plate 24 is pulled downwardlycounterclockwise about member i3, whereupon rods 22 and 23 pull downplate I! in counterclockwise direction about the bearing housing 9.Bearing housing 8, consequently, is tilted about its own axiscounterclockwise to change the tilt of shaft 8, hub 3a, and,consequently, the plane of rotor i. In like manner, if lever 29 ispulled outwardly from the plane of the paper (see Fig. 1), then plate 24is tilted in accordance therewith, such that ball and socket joint 25'and 23 may rotate without being changed vertically while ball and socketjoint 21 and 28 is lowered. In consequence, ball and socket joint 20 andill will rotate while ball and socket joint 2|, I9 is lowered andtheplane ofpl'ate ll at bearing housing 9 is thus varied to tilt theplaneof rotor in accordance with the tilt of lever 29. It is to bepointed out specifically that such movements take place irrespective ofthe position of bearing housing 9 with respect to the axis of member i4.That is, bearing housing 9 can be moving about the axis through memberi3 and still the described tilting control will be provided to bearinghousing 9 and the plane-of rotor by means of lever 21.

This new and improved support for a fuselage from a sustaining rotorgives a flexible, yet secure, control. The plane of the rotor may betilted to any desired position; the hub of the rotor may travel in anypath, being constrained only by a fixed length between the hub 3a andsupport member M. It should be noted that any lateral vibrations causedby the fact that the center of rotation of the rotor is not the exactcenter of the shaft 8, will be absorbed before the vibrations reachtheplate 24 by the double universal joints I0 and l2 and theparallelogram support including plates H and 24 and rods 22 and 23. Itis clear from the Figs. 1 and 2 that platel'l may move laterally withouttransmitting this lateral movement to plate 24. In Fig. l for instance,if plate. I] vibrates forward, balls 2D and 2| and universal joint lcwill move forward androtate with respect to'their joints. This willcause the balls 25 and 21 and universal joint 12 to rotate in theirrespective joints. The result of this is that the rods 22 and 23 andshaft II are slanted with respect to plates H and 24. It is clear thatplates l7 and 24 remain parallel, and, for the vibrations in question,the distance between the plates is not substantially changed.Furthermore, a great deal of the vibrations that are produced in theblades 2 and 3 by the fluctuation of air resistance are absorbed beforethey reach the plate 24 by the drag hinges and the flap hinges. This isthe desired end result, which is a great improvement over the prior art.

Modifications of this invention will occur to those skilled in the artand it is desired to be understood, therefore, that this invention isnot to be limited to the particular embodiment disclosed, but that theappended claim is meant to cover all the modifications which are withinthe spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

A rotary wing aircraft comprising a fuselage, a plurality of bladesconstituting a rotary wing", and the combination of a mechanism forsupporting said fuselage from said rotary wing with a linkage system forcontrolling from Within said fuselage the tilt of the plane of saidrotary wing, said supporting mechanism comprising a hub, means mountingsaid rotary blades thereon, a bearing housing having an upper and alower end, means connecting the upper end of said bearing housing tosaid hub, means connecting the lower end of said bearing housing to saidfuselage, said lower connecting means comprising an upper universaljoint, an intermediate universal joint and a lower universal jointpositioned in spaced apart relationship, means connecting the upper ofsaid universal joints to said lower end of said bearing housing, meansincluding a shaft member connecting said upper universal joint to saidintermediate universal joint, means including a joint member connectingsaid intermediate universal joint to said lower universal joint, andmeans supporting the entire load of said fuselage from said loweruniversal joint, said linkage system comprising a first plate extendingradially outwardly from said bearing housing, a second plate extendingradially outwardly from said joint member with each of said plateshaving portions spaced apart 90 with respective portions of each of saidplates overlying one another, a control lever integral with said secondplate at one end and with its other end extending into said fuselage,and a pair of substantially parallel elements connecting respectivelycorresponding overlying portions of said first and secend plates.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,224,357 Pecker Dec. 10, 1940 2,365,357 Prewitt Dec. 19, 19442,380,581 Prewitt July 31, 1945 2,395,143 Prewitt Feb. 19, 19482,487,646 Gluhareif Nov. 8, 1949 2,569,882 De Bothezat Oct. 2, 1951FOREIGN PATENTS Number Country Date 580,109 Great Britain Aug. 27, 194661,395 Netherlands July 15, 1948 OTHER REFERENCES Serial No. 254,867,Flettner (A. P. 0.), published May 25, 1943.

